Pipe Volume Calculator (Water in a Pipe)
Enter the pipe’s inside diameter and length.
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Pipe Volume Calculator (Water in a Pipe) by TheCalcTools
How the Pipe Volume Calculator (Water in a Pipe) works
Volume = π × (inside diameter ÷ 2)² × length. Use the inside diameter, which is smaller than the nominal size and depends on the pipe material and wall thickness.
Knowing the volume helps with flushing new pipes, dosing treatment chemicals and estimating how long hot water takes to arrive.
The formula
Worked example
Using the default values shown in the calculator:
| Inside diameter (mm) | 22 |
|---|---|
| Length (m) | 25 |
| Flow rate (litres per minute, optional) | 12 |
- 25 m of pipe with a 22 mm bore holds 9.503 L.
- At 12 L/min it takes 47.5 s to flush.
Result:
| Volume (litres) | 9.503 |
|---|---|
| In US gallons | 2.511 |
| Water weight (kg) | 9.48 |
| Litres per metre of pipe | 0.3801 |
| Time to fill or flush (seconds) | 47.5 |
Frequently asked questions
How long until hot water arrives?
Divide the pipe volume between the heater and tap by the flow rate. 25 m of 22 mm pipe holds about 9.5 L, roughly 48 seconds at 12 L/min.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.